Roof and wall support is vital in mining and tunneling operations. Mine and tunnel walls and roofs consist of rock strata, which must be reinforced to prevent the possibility of collapse. Rock bolts are widely used for consolidating the rock strata.
In conventional strata support systems, a hole is drilled into the rock by a drill rod, which is then removed and a rock bolt is then installed in the drilled hole and secured in place typically using a resin or cement based grout.
Self drilling rock bolts have also been proposed whereby the bolt is also used as the drill rod. As such, with a self drilling rock bolt, the hole can be drilled and the bolt installed in a single pass.
In both conventional rock bolts and self drilling rock bolts, mechanical anchoring devices are often incorporated on the bolt to retain the bolt in place when located in a drilled hole. To ensure correct installation, anchoring devices should not be prone to inadvertently activate or fail to activate when required.